A great deal of animal research has indicated that, in the acute phase of intoxication, cocaine specifically activates brain regions which are part of a "reward circuit." We have proposed a study to correlate cocaine's subjective effects on regional brain activity, using Dynamic 133 Xenon SPECT, H215O-PET,and MRSpectroscopy (CSI). Using analytical models to identify neural networks related to cocaine activation, we hope to inform future receptor-based research.